Magnetic Random Access Memory (MRAM) is a non-volatile computer memory technology based on magnetoresistance. One type of MRAM cell is a spin torque transfer MRAM (STT-MRAM) cell. A conventional STT-MRAM cell includes a magnetic cell core supported by a substrate. The magnetic cell core includes at least two magnetic regions, for example, a “fixed region” and a “free region,” with a non-magnetic region in between. An STT-MRAM cell may be configured to exhibit a vertical magnetic orientation in both the fixed region and the free region, or may be configured to exhibit a horizontal magnetic orientation in both the fixed region and the free region. The fixed region has a fixed magnetic orientation, while the free region has a magnetic orientation that may be switched, during operation of the cell, between a “parallel” configuration, in which the magnetic orientation of the fixed region and the magnetic orientation of the free region are directed in the same direction (e.g., north and north, east and east, south and south, or west and west, respectively), and an “anti-parallel” configuration, in which the magnetic orientation of the fixed region and the magnetic orientation of the free region are directed in opposite directions (e.g., north and south, east and west, south and north, or west and east, respectively). In the parallel configuration the STT-MRAM cell exhibits a lower electrical resistance across the magnetoresistive elements, i.e., the fixed region and free region. This state of relatively low electrical resistance may be defined as a “0” state of the MRAM cell. In the anti-parallel configuration, the STT-MRAM cell exhibits a higher electrical resistance across the magnetoresistive elements, i.e., the fixed region and free region. This state of relatively high electrical resistance may be defined as a “1” state of the MRAM cell. Switching of the magnetic orientation of the free region and the resulting high or low resistance states across the magnetoresistive elements enables the write and read operations of the conventional MRAM cell.
Conventional fabrication methods for forming STT-MRAM cell structures may include selective removal of materials from precursor structures of stacked materials. The materials to be removed may include elements with relatively high atomic weights, which may present a challenge to volatilization during a conventional dry etch process. Further, volatilized elements may undesirably redeposit on the structures being etched, rather than being completely removed during the etching process. Still further, as the dimensions of STT-MRAM cell structures decrease, e.g., below about thirty nanometers, so as to increase device density on a wafer, achieving uniformity in the structures of STT-MRAM cells during fabrication may present a challenge.